D the G. Being a sad person at times, I have reread all the posts on this thread. I quite like your take on the 1954 definition. I had previously missed it. If I can loosely paraphrase you (and please correct me if I have misinterpreted it) A song or tune written last week could qualify as folk if adapted and performed and re-requested.
I had not thought of such a wide interpretation and I quite like it.
For a song or tune to be selected it must push some buttons, strike some chords, have some kind of resonance with many people.
A couple of examples Garth Brooks: The River and If tomorrow never comes
I have heard both in sessions. My take is that they will become/are contemporary folk classics. (a C&W Folk meld) Such songs have the ability "raise the hair on the back of your neck), they cut to the emotions and play them like a harp. Surely this ability is a vital component of folk and runs in tandem with shuttle weavers songs etc.